Refrigeration system including charge checking means



Dec. 29, 1964 w. A. SPOFFORD REFRIGERATION SYSTEM INCLUDING CHARGE CHECKING MEANS Filed May 29, 1963 INVENTOR. WARREN A. SPOFF'ORD BY l His ATTORNEY United States Patent 3,163,015 REFRIGERATEQN SYSTEM HNKCLUBENG HARGE QHEQKEN'G MEAN Warren A. Spofford, Tyler, Tea, assignor to General Electric Company, a corporation of New York Filed May 29, 1953, Ser. No. 284,153 9 Claims. ill. 62-129) The present invention relates to refrigeration systems and is particularly concerned with a refrigeration system including means for checking the amount of refrigerant contained in the refrigerating system and for indicating when the addition of refrigerant to the system has brought the total charge up to the proper amount for normal operation.

It is Well known that during normal operation of a refrigeration system comprising a compressor, a pair of heat exchangers and means for controlling the flow of refrigerant between the heat exchangers, the amounts of refrigerant contained in the various components of the system will vary depending, for example, upon ambient temperature and load conditions so that during normal operation, the amount of refrigerant in any particular component cannot be employed as an accurate measure of the total or optimum refrigerant charge. in fact, the determination of the actual refrigerant charge contained in a refrigeration system has always been a problem particularly in the field servicing thereof. While several methods are presently available to the serviceman, none have been completely acceptable. One method commonly used comprises evacuating the system and recharging the system with a new and accurately weighed charge of refrigerant. This is wasteful in that most or all of the refrigerant in the system is lost during the evacuation. Another known method for providing a refrigeration system with the proper charge has included a comparison of the system performance with predetermined performance curves and the addition or removal of refrigerant as required. This is a time consuming operation and frequently requires the provision of a plurality of performance curves for difierent ambient or operating conditions. Furthermore, performance curves have been useful only when there are no charge storage devices, such as receivers, accumulators, or modulators in the system in which different amounts of refrigerant may collect under various normal operating conditions.

An object of the present invention is to provide a refrigeration system including means for collecting substantially the entire refrigerant charge as a liquid in an isolated portion of the system having a preselected volume and means for detecting when that portion of the system contains a quantity of liquid refrigerant representative of the proper charge.

The specific features and advantages of the present invention will become apparent as the following descrip tion proceeds and the features of novelty which characterize the invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

Briefly stated, in accordance with one aspect of the present invention, a refrigeration system essentially including a compressor, a condenser, an evaporator and flow control means for controlling the normal flow of refrigerant from the condenser to the evaporator; is provided with normally open valve means which is closed during charge checking of the system for stopping the normal flow of refrigerant from the condenser. A bypass line including flow restricting means is provided for bypassing the lower portion of the condenser and the valve means so that substantially all of the refrigerant in the system will collect as a static body of liquid in the lower portion of the condenser ahead of the closed sunsets Federated Dec. 29, 1964 valve means. When the inlet to the bypass line is connected to the condenser at a point such that the portion of the condenser between the bypass line connection and the valve means has a preselected volume substantially equal or proportional to the desired charge of liquid refrigerant for the system, the flow of liquid rather than gas through the bypass line is an indication that the proper charge has been introduced into the system.

For a better understanding of the invention reference may be had to the accompanying drawing in which:

FIGURE 1 is a diagrammatic illustration of a refrigeration system embodying the present invention;

FIGURE 2 is a diagrammatic illustration of a portion of the refrigeration system illustrating a modification of the present invention; and

FIGURE 3 is a similar illustration of a portion of a refrigerating system illustrating another modification of the present invention.

While it will be obvious that the present invention is applicable to any refrigeration system of either the cooling only or reversible types, it will be particularly described with reference to a reversible cycle system or heat pump.

Referring now to FIGURE 1 of the drawing, there is shown a reversible refrigeration system comprising an outdoor heat exchanger 1 and an indoor heat exchanger 2 which may be employed for heating or cooling an enclosure, the two heat exchangers forming part of a closed refrigerant circuit. Means in the circuit for withdrawing refri erant from either one of the two heat exchangers and discharging compressed refrigerant into the other includes a compressor 4 and a reversing valve 5. The reversing valve 5 is designed to reversibly connect the discharge line 6 and the suction line 7 of the compressor to the remaining portions of the system so that the compressor will withdraw low pressure refrigerant from either the indoor or the outdoor heat exchanger and discharge compressed refrigerant into the other of the two heat exchangers. Thus the outdoor heat exchanger 1 functions as a condenser and the indoor heat exchanger 2 as an evaporator when the system is operated on the cooling cycle while the indoor heat exchanger 2 functions as the condenser and the outdoor heat exchanger 1 as an evaporator when the system is operated on the heating cycle.

For control of the flow of refrigerant in the circuit from one heat exchanger to the other during normal operation of the system on each cycle and to provide the desired pressure differentials between the two heat exchangers, there is provided normal flow control means which in the illustrated embodiment of the invention comprises a heating cycle capillary 8 and a cooling cycle capillary 9. Each of the capillaries also has associated therewith a bypass line for bypassing that capillary during operation of the system on one or the other of the cycles. More specifically, the heating capillary 8 is provided with a. bypass line 15* including a check valve 11 which permits flow of refrigerant through the bypass line dtuing operation of the system on the cooling cycle, the capillary 9 then operating as the expansion or flow control means. Similarly a bypass line 12 including a check valve 13 bypasses most of the refrigerant flow around the capillary 9 on the heating cycle so that the heating capillary 8 then pro vides the desired normal restriction between the two heat exchangers during operation of the system on the heating cycle.

While the capillaries 3 and 9 are designed to provide different refrigerant flow rates on the heating and cooling cycles, it is also desirable in many reverse cycle systems of this type to include means for modifying or changing the amount of refrigerant flowing through the circuit in order to obtain the most efiicient operation of the system on each cycle as Well as under a range of operating conditions on either cycle. In the illustrated embodiment of the invention, this is accomplished by means of two deadend or two-way flow storage receptacles associated respectivoly with the portions of the circuit on the opposite sides of the fiow contol means. More specifically, the system includes a dead-end storage receptacle 14 connected by a two-way flow line 15 to a portion of the circuit such as the line 1'? connecting the bottom end it; of the heat exchanger to the flow control means, which portion operates at the same pressure as the heat exchanger 1. The second receptacle 19 is similarly connected by means of a connection 20 to a portion of the circuit between the indoor heat exchanger 2 and the flow control means. For the purpose of effecting automatic withdrawal of refrigerant from the system or automatic discharge of refrigerant into the flow circuitry by one or both of these receptacles in order to regulate or change the effective circulating charge under various conditions of operation, the receptacle 14 is heat exchanged with the conduit 22 which connects the reversing valve 5 with the end 23 of the outdoor heat exchanger 1 while the receptacle 19 is heat exchanged with the conduit 2% connecting the reversing valve 5 with the indoor heat exchanger 2. Thus when the system is operated on the cooling cycle so that hot compressed refrigerant is being conducted from the coinpressor 4 to the heat exchanger 1 through the conduit 22, the receptacle 14 is warmed by this hot refrigerant causing most or all of my liquid refrigerant contained or stored in the receptacle to be discharged into the refrigerant flow circuit. During the same cycle of operation, the receptacle 19 is cooled by low pressure refrigerant returning to the compressor through the conduit 24 so that refrigerant will be Withdrawn from the system and by condensation thereof be stored in the receptacle 1?. Conversely, during the heating cycle refrigerant will tend to be stored in the receptacle 14 due to the cooling eifect of the low pressure refrigerant then flowin through the line 22; While the refrigerant will tend to be discharged from the receptacle 19 due to the warming effect of the compressed refrigerant flowing from the compressor to the indoor heat exchanger 2 through the conduit 24. The withdrawal from or the addition to the circuit of refrigerant by the modulator receptacles 14 and 19 is influenced not only by the heat exchange thereof with certain portions of the circuit but also by the particular system pressure and temperature conditions in those portions of the system to which these receptacles are respectively connected by the connections 15 and 29.

When a refrigeration system is manufactured and sold as a unit, it is normally precharged with the proper charge of refrigerant before leaving the factory. However, if components of the system are connected together to form a complete system during field installation or if it becomes necessary to 'field service a system in which the existing charge may be of unknown quantity due to leakage, it is necessary to provide some means for indicating when the charge in the system has been brought up to that amount required for normal operation of the system. To this end, there is provided in accordance with the present invention means for operating the system on a charge determining cycle during which most of the refrigerant is condensed as a liquid in an isolated portion of the system and means for indicating when the volume of liquid so collected represents the proper charge for the system.

In the embodiment of the invention shown in FIGURE 1, the charge determining or measuring means comprises a normally open valve 26 at the lower end of the heat exchanger 1 or in other words at the end of the condenser which functions as the outlet when the system is being operated with the heat exchanger 1 functioning as a condenser. Tln's valve 26 includes a front seat 27 and a back seat 28. The valve is normally back seated so that there is unrestricted flow of refrigerant between the heat exand the ilow control means including the capillaries o d during normal operation of the system on either the heating or he cooling cycle. A bypass line 29 including a fixed flo'v restricting means or capillary 3t bypasses front seat 2? of the valve 26 and is connected through the back seat 28 with the line 17 connecting the lower end of the heat exchanger 1 to the liow control means. The other end of the bypass line 29 is connected as at :3 to the heat exchanger 3 a distance from the valve 26 such that the volume of the portion of the condenser between the connection 31 and the valve 26 is substantially equal to or proportional to the liquid volume of the optimum or preferred charge of refrigerant for the system.

in order to determine when the proper charge has been introdi ed into the system, the system is operated on a charge determining cycle in which the compressor 5 is operated with the switch-over or reversing valve 5 set so that the compressor pumps refrigerant through the system in a direction such that the heat exchanger 1 functions as a condenser or in other Words as part of the high pressure component of the system. The valve 26 is front seated to close the seat 27 thereby interrupting normal flow of refrigerant from the heat exchanger 1 to the line The bypass line 2-,? including the flow restriction 3% then permits limited circulation or flow of refrigerant around the valv 2e and into the line l7 and the lower portion of the heat exchanger 1 between the inlet connection 31 and valve 26 is isolated from the circuit. Any refrigerant in the system collects as a liquid in this portion of the heat exchanger 1. If the refrigerant charge in the system is insufiicient to till the lower portion of the heat exchanger 1 up to the inlet end 33., only gaseous refrigerant will flow through bypass line 29 which is preferably connected to the upper portion of one of the return bends 32 to prevent entrance of liquid into the bypass line 29 in case both liquid and gaseous refrigerant are present at this portion of the heat exchanger.

For most systems, operation of the compressor for a period of time up to 15 minutes is sufficient to transfer substantially all of the refrigerant charge to the high pressure side of the system leaving the remaining portions of the system containing only low pressure gaseous refrigerant. To assure this result, the flow restriction provided by the flow restricting means 36 is preferably somewhat greater than the flow restriction offered by either the capillaries 8 or 9 so that the pressure in the high pressure side of the system is hig er than normal while the pressure in he low pressure side is lower than normal. These pressure conditions then assure quick vaporization of liquid refrigerant contained in the components of the system other than the heat exchanger 1 and assure the transfer thereof to the heat exchanger 1. During this period of operation. the receptacle M is warmed by the refrigerant flowing through the line 22 for vaporization of any liquid refrigerant contained therein. The receptacle i? connected to a low pressure side of the system operates at a lower than normal pressure such that any liquid refrigerant contained in this component will also be evaporated and transferred to the heat exchanger 1.

In the operation of the system illustrated in FIGURE 1, a change in system pressure conditions is employed to indicate when the liquid in the lower portion of the heat exchanger 1 rises to a level such that liquid rather than gaseous refrigerant flows through the bypass line 29. As is Well known, a fixed flow restricting means such as the capillary 3 8 will pass a liquid at a greater weight flow rate than a gas for given upstream downstream pressures. Thus when liquid instead of gas enters the bypass line 2%, the resultant increase in refrigerant flow will be indicated promptly by substantial changes in suction and discharge pressures at the compressor. Since a larger quantity of refrigerant is then being introduced into the low pressure side of the system, the suction pressure will changer l rise so that a pressure indicating means such as a pressure guage 34 connected for example to the suction line 7 can be employed to indicate the passage of liquid rather than gaseous refrigerant in the line 29.

This change in the suction pressure resulting from a change of flow rate can perhaps best be understood from a consideration of the manner in which suction pressure will change as the amount of refrigerant contained in the system is increased. For example, the initial addition of refrigerant to a system starting from a vacuum in the system results at first only in the circulation of superheated refrigerant vapor throughout the system and the suction pressures throughout the system will be low. As the addition of refrigerant is continued, the gas pressures will increase and when there is a sufficient weight of refrigerant in the system so that condensation occurs in the heat exchanger 1, liquid refrigerant will start to collect in the bottom of this heat exchanger. For a period of time thereafter, nearly a constant value of suction pressure will prevail as more refrigerant is added since this additional refrigerant is being continuously condensed in the lower part of the heat exchanger 1 and thus removed from the circuit. However, as soon as the liquid in the bottom of the heat exchanger rises so as to enter the inlet to the bypass line 29, the flow of liquid refrigerant to the low pressure side of the system causes the suction pressure to rise rapidly until it again levels off at a higher value determined by the liquid flow rate of the flow restrictor 30. This leveling off of the suction pressure is an indication that there is sutficient charge in the system to fill the preselected volume of the lower portion of the heat exchanger 1. The charging cycle is then terminated by back seating the valve 26. The suction pressure will then rise to a new level which is appropriate for the normal flow rate of the control or expansion means 9.

In order to obtain a relatively sharp line of division between the gas and liquid fiow through line 29 and therefore a sharp change in the suction pressure when the required amount of refrigerant has been added to the system, it is desirable that the inlet portion of the bypass line 29 ahead of the flow restricting means 31 be sufiiciently large so that the velocity of the gas flowing therethrough will be such that it will not mechanically carry liquid refrigerant into the bypass line 29 and hence into the low pressure side of the system.

In the form of the invention illustrated in FIGURE 2, a sight glass 35 provided in the bypass line 29 rather than a change in the system suction pressure is employed as means for indicating the change from gas to liquid flow through this line. The sight glass shows only gaseous refrigerant until such time as the amount of liquid collected in the heat exchanger 1 is sufiicient to fill it up to the inlet 31 after which there is a liquid flow past the sight glass 35. Thus it will be seen that the sight glass performs the same function as the pressure gauge 34-. While the sight glass 35 is shown as being positioned adjacent the inlet end of the line 29, upstream from capillary 30, it will be understood that it can also be positioned downstream from the capillary 30 so that it would show the gaseous or liquid refrigerant leaving this flow restricting means or would show a substantial change in the character of the refrigerant leaving the flow restrictor 3%) when the liquid level reaches the inlet 31.

In a heat exchanger containing two or more parallel paths as illustrated in FIGURE 2, the line 29 may be connected to one of the paths and a sight glass 36 provided at the appropriate height in the other path. Since the two paths are interconnected, the liquid levels in the two will be approximately equal so that a liquid-gas interface observed in glass 36 at the same height as inlet 31 will also indicatethe beginning of liquid flow through line 29. The placing of sight glass 36 in a path not connected to line 2 has an additional advantage in that there is no flow of refrigerant at this point so that it is easier to detect when the liquid builds up to its level. It will also be obvious that the sight glass 36 can be positioned below the level of inlet 31 but at a level indicating the proper charge of liquid refrigerant and the addition of refrigerant stopped when the liquid-gas interface is observed in the sight glass.

In the embodiment of the invention illustrated in FIG- URE 3, additional means are provided for avoiding the entrainment of liquid refrigerant entering the inlet end of the bypass line 29. At the same time provision is made for a greater total volume of refrigerant to pass through the bypass line so that a larger load may be imposed on the compressor and a larger amount of refrigerant will be passed through the compressor motor for cooling purposes. To this end, a second connection to the bypass line 25 is made at a point near the top of the heat exchanger 1 or in other words at the point well above the inlet connection 31 and where only gaseous refrigerant is present. This connection, as at 36, includes a fiow restrictive section 37 connecting directly to the fiow restrictive means 30. The gas flowing through this restrictive passage 37 passes into the flow restrictive means 39 after being joined by the flow through the main bypass line 29. The portion of the bypass line 29 between its inlet 31 and the connection with the restriction 37 will now pass only a fraction of the total fiow of refrigerant being circulated through the system so that a better liquidgas separation can be obtained at the lower flow rate. The restriction 37 need only be sufiiciently restricted to give a pressure difference to lift liquid through the inlet end of the bypass line 29 when the liquid level rises to the level of the inlet 31. This lifting of liquid instead of gas will cause a relatively high flow rate by weight of fiuid through the bypass line and thereby increase the load on the compressor or more specifically increase the suction pressure as measured by the pressure gauge 34. If a sight glass such as sight glass 35 or 36 is employed the liquid flow or level will be indicated by such indicating means.

While the invention has been described with particular reference to a reversible refrigeration system, it is applicable to either cooling or reverse cycle systems of various types including self-contained refrigeration systems and remote or split-type systems in which the indoor and outdoor sections are some distance apart and connected by extended liquid and gas lines. It will also be obvious that the charge determining means is equally applicable to systems which employ thermostatic expansion valves in place of the capillary tubes 8 and 9.

Additional modifications of the invention will occur to those skilled in the art and it is to be understood therefore that the invention is not limited to the particular embodiments disclosed and that it is inended to cover by the appended claims all modifications which are within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a refrigeration system including a compressor, a first component adapted to be operated as a condenser, and a second component adapted to be operated as an evaporator connected in closed series fiow connections; means for determining the refrigerant charge in said system comprising valve means in said system between said components for stopping the normal flow of refrigerant from said first component to said second component so that while said compressor is operating substantially all of the refrigerant charge in said system will collect as a liquid in said first component ahead of said valve means, and means for determining whether the charge of refrigerant in said system is proper for normal operation thereof comprising a restrictive flow means bypassing said valve means and having its inlet connected to said first component at a point such that the portion of said first component between said point and said valve means has a volume representing the proper charge of refrigerant for said system, and means in said system for indicating flow of liquid refrigerant through said restrictive flow means.

2. In a refrigeration system including a compressor, a first component adapted to be operated as a condenser and a second component adapted to be operated as an evaporator; means for determining the refrigerant charge in said system comprising normally open valve means between said components for stopping the normal flow of refrigerant from said first component to said second component when closed and a bypass line including flow restricting means bypassing said valve means and adapted to cause substantially all of the refrigerant in said system to collect as a liquid in said first component ahead of 7 said valve means when said compressor is operating and said valve means closed, the inlet end of said bypass line being connected to said first component at a point such that said line will conduct only gaseous refrigerant when said system contains substantially less than the proper charge and will conduct liquid refrigerant when the system contains more than the proper charge.

3. In a refrigeration system including a compressor, a first component adapted to be operated as a condenser, and a second component adapted to be operated as an evaporator connected in closed series flow connection for normal flow of refrigerant from said first component to said second component; means for determining the re it'rigerant charge in said system comprising valve means between said components for stopping the normal fiow of refrigerant irom said first component to said second component and means bypassing said valve means for providing restricted flow of refrigerant from a point in said first component spaced from said valve means to said second component whereby While said compressor is operating said restricted flow means will cause he refrigerant charge in said system to coll ct as a liquid in the portion of said first component between said point and said valve means, said portion having a liquid storage volume substantially equal to that representing the liquid volume of the desired charge of refrigerant for said system, said first component including means for indicating when the level of liquid refrigerant in said first component is substantially at said point.

4. In a refrigeration system including a closed refrigerant circuit comprising a compressor, a first heat exchanger adapted to operate as a condenser and second heat exchanger adapted to operate as an evap rator; means for determining when the charge of ref in said system is proper for normal operation or" said system comprising valve means in said system between said heat exchangers for stopping normal how of refrigerant from said first heat exchanger to said second heat exchanger and restrictive flow means bypassing said valve means whereby substantially all of the refrigerant in said system will collect as a liquid in the portion of said circuit ahead of said valve means, the inlet end of said restrictive flow means being connected to said circuit be tween said compressor and said valve means at a point such that the portion of said circuit between said connecting point and said valve means will be exactly filled with liquid refrigerant when the proper charge of liquid refrigerant is present in said system.

5. In a refrigeration system including a closed refrigerant circuit comprising a compressor, a first heat. exchanger adapted to operate as a condenser, a second heat exchanger adapted to operate as an evaporator and ilow control means for normally controlling flow of refrigerant between said heat exchangers; means for det mining when a charge of refr gerant being introduced to said system is proper for normal operation of said system comprising valve means in said system between said heat exchangers for stopping normal how of refrigerant from said first heat exchanger to said second heat exchanger and a line including restrictive iiow means bypassing said valve means whereby when said compressor is operating substantially all of the refrigerant in said system will collec as a liquid in tae portion of said circuit ahead of said valve means, the inlet end of said line being connected to said circuit h veen said compressor and said valve means at a point such that the portion of the circuit between said inlet and said valve means has a volume sufficient to contain in he form a predetermined volume of liquid refrigerant i 'v'e or" the proper charge whereby as a refrigerant is intr duced into said systcir, liquid refrigerant will fiow through said restrictive flow means when the pro r cha 'ze has been introduce 6. in a refrigeration system including a closed refrigerant circuit compizsing a compressor, a first heat exchanger adapted to operate as a condenser, 11 second heat e changer adapted to operate as an evaporator and flow control for normally controlling flow of refrigerant between said heat exchangers; means for determining when the charge ol ref igerant in said system is proper for normal operation of said system comprising valve means in said system between said heat exchangers for stopping flow of refrigerant from said first heat exchanger to said second heat exchanger and a line including restrictive means bypassing said valve means and having its inlet connected to said circuit between said compressor and said valve means at a point to isolate the portion of said circuit between said inlet and said valve means in which a static body of liquid refrigerant can collect. said line conducting gaseous refrigerant when the level of said body of liquid refrigerant is below said inlet, and a second restrictive flow connection between said restrictive flow means and said circuit ahead of said inlet connection for permitting a continuous flow of gaseous refrigerant therethrough to prevent entrainment of liquid refrigerant by the gaseous refrigerant flowing into said inlet end connection.

7. In a refriger :1 system comp":ing a condenser having outlet at the bottom thereof, an evaporator, normal flow control means connecting said condenser onlet to said evaporator, and a compressor for withdrawing gaseous refrigerant from said evaporator and discharging compressed refrigerant to said condenser; means for indieating when the proper cha ge of refrigerant has been introduced into said system during the charging thereof with the compressor operating comprising valve means for stopping flow of refrigerant from said condenser outlet and a line inclu g abnormal flow restrictive means by passing said valve for limiting the tlow of refrigerant through said system to cause substantially all of the refrigerant in said system to collect as a liquid in said condenser, said line having t end connected to said condenser at a point above said outlet such that the volume of liquid refrigerant collected in said condenser w ien said line beg ns to conduct liquid refrigerant constitutes the proper charge for said system.

S. in a refrigeration system comprising a condenser having an outlet at the bottom thereof an evaporator, normal fiow control means connecting s condenser out let to said evaporator, and a compressor for Withdrawing gaseous refrigerant from said evaporator and discharging compressed refrigerant to said condenser; for indicating the proper charge or refrigerant has been introduced into said system during the c arging thereof with the compressor operating comprising valve means for stopping flow of refrigerant from said condenser outlet so that refrigerant will collect as a li 'd said condenser ahead of said valve means, Lu? including abnormal iiow restrictive means bypassing said valve and rig is inlet end connected to said condenser at a point above said outlet :1 dist see such that the volume of the portion of said condone r between d i lct connection and said valve substan lly equals the li uid volume of the proper charge for said system; and means in said bypass lin pass line begins its 1 9 having an outlet at the bottom thereof, an evaporator, normal flow control means connecting said condenser outlet to said evaporator, and a compressor for withdrawing gaseous refrigerant from said evaporator and discharging compressed refrigerant to said condenser; means for determining when the proper charge of refrigerant has been introduced into said system during the charging thereof with the compressor operating comprising valve means for stopping flow of refrigerant from said condenser outlet during the charging period and a line including abnornal flow restrictive means bypassing said valve, said line having its inlet end connected to said condenser at a point above said outlet such that the volume of the portion of said condenser between said inlet connection and said valve substantially equals the liquid volume of the proper liquid charge for said system, whereby the flow of liquid refrigerant through said bypass line is an indication that the proper charge of refrigerant has been added to said system, and a restrictive connection between said bypass line and a point in the condenser above said inlet connection for introducing sufficient gaseous refrigerant into said bypass line to provide gas liquid separation at said inlet connection.

References Cited by the Examiner UNITED STATES PATENTS 1,533,336 10/24 Pownall 62292 1,744,287 1/ 30 Tibbetts 62-292 1,815,962 7/31 Andrews 62149 2,049,364 7/ 36 Fisher 62-292 2,69 1,279 10/ 54- Anderson 62292 2,977,773 4/61 Kanter 62149 ROBERT A. OLEARY, Primary Examiner; 

1. IN A REFRIGERATION SYSTEM INCLUDING A COMPRESSOR, A FIRST COMPONENT ADAPTED TO BE OPERATED AS A CONDENSER, AND A SECOND COMPONENT ADAPTED TO BE OPERATED AS AN EVAPORATOR CONNECTED IN CLOSED SERIES FLOW CONNECTIONS; MEANS FOR DETERMINING THE REFRIGERANT CHARGE IN SAID SYSTEM COMPRISING VALVE MEANS IN SAID SYSTEM BETWEEN SAID COMPONENTS FOR STOPPING THE NORMAL FLOW OF REFRIGERANT FROM SAID FIRST COMPONENT TO SAID SECOND COMPONENT SO THAT WHILE SAID COMPRESSOR IS OPERATING SUBSTANTIALLY ALL OF THE REFRIGERANT CHARGE IN SAID SYSTEM WILL COLLECT AS A LIQUID IN SAID FIRST COMPONENT AHEAD OF SAID VALVE MEANS, AND MEANS FOR DETERMINING WHETHER THE CHARGE OF REFRIGERANT IN SAID SYSTEM IS PROPER FOR NORMAL OPERATION THEREOF COMPRISING A RESTRICTIVE FLOW MEANS BYPASSING SAID VALVE MEANS AND HAVING ITS INLET CONNECTED TO SAID FIRST COMPONENT AT A POINT SUCH THAT THE PORTION OF SAID FIRST COMPONENT BETWEEN SAID POINT AND SAID VALVE MEANS HAS A VOLUME REPRESENTING THE PROPER CHARGE OF REFRIGERANT FOR SAID SYSTEM, AND MEANS IN SAID SYSTEM FOR INDICATING FLOW OF LIQUID REFRIGERANT THROUGH SAID RESTRICTIVE FLOW MEANS. 